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Chemistry > Chapter 1 - Elements Of Life > Flashcards

Chapter 1 - Elements Of Life Flashcards

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1
Q

What’s the test for cations

A

Add NaOH to form a precipitate of metal hydroxide then add excess

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2
Q

Identifying Cu2+

A

Add NaOH

Blue ppt of Cu(OH)2

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3
Q

Identifying Fe2+

A

Add NaOH

green ppt of Fe(OH)2

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4
Q

Identifying Fe3+

A

Add NaOH

Brown ppt of Fe(OH)3

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5
Q

Identifying Al3+

A

Add NaOH

White ppt that dissolves

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6
Q

Identifying Ca2+

A

Add NaOH

White ppt of Ca(OH)2

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7
Q

What’s the test for carbonate ions

A

Add HCl then test gas with limewater

Carbonates make limewater cloudy

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8
Q

What’s the test for Sulfate ions

A

Add conc HCl to react with any carbonates
Then add barium chloride solution
Sulfate ions cause a white ppt of barium Sulfate to form

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9
Q

What’s the test for halide ions

A

Add conc nitric acid to react with any carbonates then add silver nitrate

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10
Q

Identifying Cl-

A

Add conc nitric acid
Then silver nitrate
White ppt will form

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11
Q

Identifying Br-

A

Add nitric acid
Then silver nitrate
Cream ppt forms

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12
Q

Identifying I-

A

Add nitric acid
Then silver nitrate
Yellow ppt forms

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13
Q

What’s the test for ammonium ions

A

Heat sample with NaOH
Alkaline NH3 gas produced
Turns damp red litmus paper blue

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14
Q

What’s the test for nitrate ions

A

Heat sample with devardas alloy
Add NaOH
Then add damp red litmus

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15
Q

What’s the test for primary and secondary alcohols

A

Add acidified potassium dichromate
Primary and secondary react, tertiary doesn’t
Colour change of orange - green

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16
Q

What’s the test for carboxylic acids and phenols

A

Add Na2CO3
Carboxylic acid gives off CO2
Phenols don’t

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17
Q

What’s the test for alkenes

A

Add Br2
C=C react
Goes orange - colourless

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18
Q

What’s the test for amines/ammonia

A

Add conc HCl fumes

Produces white smoke of NH4Cl

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19
Q

What’s the test for aldehydes

Tollens reagent

A

Add tollens reagent
Silver mirror forms
Aldehyde is oxidised to carboxylic acid as silver ions are reduced to metallic silver

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20
Q

What’s the test for aldehydes

Fehlings

A

Add fehlings solution
Blue - brick red ppt forms
Cu2+ reduced to Cu+

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21
Q

What’s the test for phenols

A

And FeCl3

Orange - purple

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22
Q

How to make a standard solution from a solid

A
  • calculate mass of solute needed and weight it in a weighing bottle
  • pour 100cm3 distilled water into 250cm3 beaker and add solid
  • reweigh to find mass of solid added
  • stir until all solid is dissolved
  • transfer the solution into 250cm3 volumetric flask and rinse beaker several times
  • add distilled water until the water mark
  • insert stopper and invert
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23
Q

how to make a standard solution by dilution

A
  • use a bulb pipette rinsed with the solution and transfer 25cm3 of the solution to a 250cm3 volumetric flask
  • add distilled water until the meniscus is at the mark
  • insert stopper and invert several times
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24
Q

what is a mole

A

the amount of substance which contains as many atoms as there are atoms in 12grams of Carbon 12

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25
Q

what is avogadros constant

A
  • 6.02x10^23

- the number of atoms in 12grams of carbon12

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26
Q

what is the mol, mass, mr formula

A

Mass = Mr x Moles

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27
Q

definition of empirical formula

A

the simplest whole number ratio of elements in a compound

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28
Q

how to calculate empirical formula

A
  • divide by the Ar
  • find the ratio
  • simplify
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29
Q

what is the conc, vol, mol formula

A

mol = conc x vol

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30
Q

whats 1dm3 in cm3

A

1000cm3

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31
Q

how to set up an acid-base titration

A
  • rinse burette with acid then fill with acid
  • record initial burette reading
  • fill clean pipette with alkaline solution and transfer into conical flask
  • add 2 or 3 drops of indicator, swirl and place on white tile
  • run the acid from the burette into the flask, swirling continuously
  • when colour changes record final burette reading
  • repeat titration, adding acid dropwise when close to endpoint
  • repeat until you get concordant results
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32
Q

what are alkalis

A

bases that dissolve in water to form aqueous solutions containing hydroxide ions

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33
Q

metal hydroxide + acid =

A

salt + water

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34
Q

metal oxide + acid =

A

salt + water

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35
Q

metal carbonate + acid =

A

salt + water + carbon dioxide

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36
Q

metal + acid =

A

salt + hydrogen

37
Q

percentage yield formula

A

actual/theoretical x100

38
Q

why do very few chemical reactions have 100% yield

A
  • raw materials may not be pure
  • some of the product may be left behind in apparatus
  • the reaction may not have completely finished
  • some reactants may give unexpected products
39
Q

formula of ammonium

A

NH4+

40
Q

formula of copper ion

A

Cu2+

41
Q

formula of zinc ion

A

Zn2+

42
Q

formula of lead ion

A

Pb2+

43
Q

formula of nitrate ion

A

NO3^-

44
Q

formula of sulfate ion

A

SO4^2-

45
Q

formula of carbonate ion

A

C03^2-

46
Q

formula of hydrogen carbonate ion

A

HCO3^-

47
Q

how did mendeleev arrange the periodic table

A
  • in order of increasing atomic mass
  • he left gaps for elements that hadnt been discovered
  • arranged into groups with similar properties
48
Q

how is the modern periodic table arranged

A
  • in order of atomic number
  • more elements have been discovered so gaps are filled
  • has the noble gases
49
Q

explain the trend in first ionisation enthalpy of period 3 elements

A
  • overall increases as you move right

- increasing nuclear charge while same number of energy levels so electrons are the same distance from nucleus

50
Q

explain the trend in atomic radii of period 3 elements

A
  • decreases as you go right

- increasing nuclear charge attracts the electrons closer to the nucleus

51
Q

explain the trend in electrical conductivities of the period 3 elements

A
  • increases from Na to Al. decreases to Si.
  • P,S, Cl dont conduct
  • Na, Mg and Al are metals (good conductors)
  • Si is a semiconductor
  • P, S, Cl are simple molecules (dont conduct)
52
Q

explain the trend in melting and boiling points of the period 3 elements

A
  • Na -> Al has increasing melting and boiling points since they are metals (metallic bonding)
  • Si has highest MP and BP since it has giant covalent structure like diamond
  • P, S, Cl have low MP and BP since they form simple molecules with weak IMF
53
Q

metal + water =

A

metal hydroxide + hydrogen

54
Q

metal oxide + water =

A

metal hydroxide

55
Q

metal + oxygen =

A

metal oxide

56
Q

how do you find Ar (relative atomic mass)

A

multiply % abundance of each isotope by its mass number and divide the total by 100

57
Q

how does a time of flight mass spectrometer work

A
  • atoms/molecules are injected
  • ionised by electron bombardment
  • accelerated by electric fields
  • the heaviest particles are accelerated least and so reach the end of the drift region last
  • ion detector produces a read out of the % abundance of each isotope
58
Q

who formed the plum pudding model

A

JJ Thomson

59
Q

who discovered atoms have nuclueses

A

Rutherford

fired alpha particles at gold foil and they got deflected from the gold nucleuses

60
Q

who discovered the neutron

A

James Chadwick

61
Q

% uncertainty formula

A

uncertainty x 100 / measurement

62
Q

how to calculate uncertainty

A

0.5 x scale of equipment used

63
Q

formula to calculate the energy of a photon

A

frequency x plancks constant

64
Q

formula to calculate the wavelength of light

A

speed of light / frequency

65
Q

whats plancks constant

A

6.63x10^-34

66
Q

whats value of speed of light

A

3x10^8 ms-1

67
Q

definition of 1st ionisation enthalpy

A

the enthalpy change when one mole of electrons is removed from 1 mole of atoms in the gas state

68
Q

why doesn’t calcium tend to form Ca3+ ions

A

because the 3rd ionisation enthalpy is much higher as it involves removing electrons from the 3p orbital. this is closer to the nucleus and is less shielded by outer electrons

69
Q

whats the trend in ionisation enthalpy down a group

A

decreases as atoms get larger so outer electrons are further from the nucleus and theres more shielding so its easier for outer electrons to be removed

70
Q

whats the trend in ionisation enthalpy across a period

A

increases - as atomic number increases, the charge on the nucleus increases so the electrons are more strongly attracted to the nucleus

71
Q

What is atomic emission spectra and how is it formed

A
  • electron falls between energy levels
  • photon emitted
  • bigger energy gap between energy levels = higher energy photons emitted
  • higher energy photons have higher frequency
  • black background and coloured lines
72
Q

What does the atomic absorption spectrum show and how is it formed

A
  • white light is shone through a sample causing electrons to become excited between energy levels so some specific frequencies of light are absorbed
  • black lines on a coloured background
73
Q

What are giant ionic structures

A
  • Structures made from metals bonded to non-metals
  • metals become positive ions by losing electrons and non metals become negative ions by gaining electrons
  • positive and negative ions are attracted by electrostatic forces to form an ionic lattice
74
Q

What are properties of giant ionic structures

A
  • high melting points
  • don’t conduct as solids
  • can conduct when Molten/ aqueous as ions can move
75
Q

What are simple molecular structures

A
  • when atoms share pairs of electrons and nuclei attracted to electrons, forming molecules
76
Q

What are properties of simple molecular structures

A
  • strong covalent bonds within molecule
  • weak IMF between molecules
  • don’t conduct electricity
  • low melting and boiling point as little energy needed to break IMF between molecules
77
Q

What are giant covalent structures

A
  • where atoms are tetrahedrally arranged in giant networks

- eg diamond, silicon dioxide and graphite

78
Q

What are properties of giant covalent structures

A
  • high melting point
  • strong
  • hard
  • don’t conduct electricity as there’s no delocalised electrons
79
Q

Describe the structure of graphite

A
  • giant covalent
  • Carbon atoms bonded in planar sheets
  • each carbon forms only 3 bonds
  • weak IMF between layers making it soft and slippery
  • each Carbon has a spare electron which is delocalised and can move so can conduct
80
Q

What does the electron pair repulsion theory say

A

Groups of electrons around a central atom will repel each other to the maximum extent possible

81
Q

What is the shape of methane (CH4) and it’s bond angle

A
  • tetrahedral

- 109

82
Q

What is the shape of SF6 and it’s bond angle

A
  • octahedral

- 90

83
Q

What is the shape of BF3 and it’s bond angle

A
  • triangular planar

- 120

84
Q

What is the shape of BeCl2 and it’s bond angle

A
  • linear

- 180

85
Q

What is the shape of NH3 and it’s bond angle

A
  • pyramidal

- 107

86
Q

What is the shape of H20 and it’s bond angle

A
  • bent

- 104.5

87
Q

What is the shape of CO2 and it’s bond angle

A
  • linear

- 180

88
Q

What effect does a lone pair of electrons have on the bond angle of a molecule

A

Each lone pair takes 2.5 off bond angle

89
Q

What is nuclear fusion

A

When atoms collide with sufficient energy to overcome the repulsive forces between their positively charged nuclei so that the nuclei can fuse together to form a heavier element

Chemistry (7 decks)

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